I put a Bonty XR4 2.35″ tyre on a 47mm rimmed wheel (tubed). The tyre comes up 5mm wider than on 23mm rim, which I did expect.

On a ‘normal’ 23mm rim I inflate to around 28-30psi. On the 47mm rim at 20psi I started to worry that more pressure was pushing the rim strip out too much, so let it down to around 16psi. It would probably be fine lower.

I didn’t expect such a large reduction in pressure to be possible from the rim size change. Anyone else any experience and / or an explanation of this?

pressure = force / area

thats my thinking anyway. my friend argues that rim width doesnt play a part in being able to run your tyres at lower pressures, but that its to do with the tyre wall thickness.